The jack bean lectin, concanavalin A (Con A), binds saccharides containing glucose or mannose residues in a manner analogous to an antigen-antibody reaction. The lectin precipitates glycoproteins containing the appropriate sugar residues and selectively agglutinates tumor cells. Although Con A is widely used as a probe to reveal alterations in the composition and organization of tumor cell membranes, little is known about the molecular properties of the agglutinin that are responsible for its binding and agglutinating activities. In order to provide insights into possible modes of interaction of the lectin with carbohydrate determinants of normal and transformed cells, it is necessary to understand the mechanism of binding of simple saccharides to the lectin, and to determine the molecular properties of the protein associated with its carbohydrate binding specificity. We have recently described the use of C13 nuclear magnetic resonance (nmr) techniques for determining structural and dynamic information of the molecular interactions between monosaccharides and Con A. The objectives of this proposal are to extend these studies using similar nmr techniques to 1) investigate the mechanism of binding of oligosaccharides to Con A; 2) determine the topography and location of the carbohydrate binding site in each monomeric unit of the protein, and 3) investigate the molecular properties of the protein including its metal ion binding activity.